# 14.18. What is CVS?

It is an acronym for Concurrent Versions System. It is a version control system and is based on RCS (Revision Control System), but offers more functionality. It is used to maintain source code under development. It will keep multiple versions of things (handy if you broke something and have to back up and get a clean old version), and allows people remote access over the Net to pick up the latest source code and even to check in new stuff if they have permission. It is also open source (you pay for support if you want it), and since it is free it is the system of choice for people writing more free products, such as KDE.